ON COLLECTING AND PRESERVING PLANTS 33 



have a little label or ticket with the same number, while one label 

 only need have the full particulars. 



When the specimens are quite dry and stiff they can be packed 

 close together, with only a single sheet of paper between each layer, 

 and this paper need not be absorbent, but if it is unglazed the 

 specimens will keep in position better when travelling, and not 

 slip about so readily if the parcel is not quite tight. 



In hot countries it is desirable to poison collections of dried plants 

 by painting them over with a solution of mercuric chloride or 

 corrosive sublimate, to protect them against insects. This is done 

 at Kew Herbarium, and also by a few amateur Botanists in this 

 country ; but in England it is not really necessary, if camphor or 

 napthaline be freely used, as is the case in the National Herbarium 

 at South Kensington. In addition to spoiling some specimens, 

 and to the subsequent pecuUar blackening of the mounting paper 

 in many cases, and to the offensive fumes which in hot weather 

 sometimes rise from specimens treated with corrosive sublimate, 

 the solution is, of course, a most deadly poison, and must be handled 

 with great care. 



The preservative solution used at Kew is as follows : 



^ oz. corrosive sublimate, 



I oz. carbolic acid, 



I pint methylated spirit. 



It is better that the specimens should be quite dry before they 

 are poisoned. It is usually done with a large camel-hair brush, 

 but there should be no metal mountings about it, and all steel 

 instruments such as knives, scissors, or forceps must be kept away 

 from the solution or it will quickly corrode them. If the solution 

 contains too much chloride of mercury a white crystalhne deposit 

 will be left on the specimens. But we say again emphatically 

 that in this country ' the game is not worth the candle.' If further 

 proof be needed it may be mentioned that the writer has in his own 

 herbarium many hundreds of perfect specimens collected eighty or 

 more years ago which were never ' poisoned,' but which have 

 suffered nothing !rom the attacks of insects, and are to-day as 

 complete and in as good condition as ever. 



It has been customary in this country to mount dried plants on 

 paper by means of paste, good gum, or hquid glue. When fre- 

 quently handled this may have its advantages, and especially if 

 little envelopes containing loose portions of the flower and fruit are 

 attached for careful examination or dissection ; but many amateur 

 botanists attach their specimens to the paper with narrow strips 

 of gummed paper, so that they can be examined on both sides, and 

 altogether removed if desired. The little rolls of transparent 

 adhesive paper sold by stationers for repairing torn music, books, 

 etc., cannot be improved upon for this purpose. Another method 



